The purpose of this project is to determine the effect of somatosensory deafferentation of fetal primates on their postnatal behavioral development. Through use of intrauterine surgical techniques, immature fetuses are exteriorized, subjected to dorsal rhizotomy, and then replaced in utero for completion of embryonic development. Following delivery the infants are subjected to behavioral evaluation. In previous work, intrauterine deafferentation of one or both forelimbs was carried out two-thirds of the way through gestation. In an initial series severe spinal cord damage prevented conclusive interpretation of the results. In work on the current grant, prosthetic bridges were emplaced at time of fetal operation; they have successfully protected the spinal cord from damage. Motor function in the deafferented limbs of 12 months of age (at the time of this writing) is extensive and as good as that of animals deafferented during the neonatal period. Three years ago, an animal given dorsolateral prefrontal cortex ablation two-thirds of the way through gestation survived Casearian section and subsequently showed much greater sparing of function than animals given the same lesion during infancy; it is indistinguishable from normal animals on the behavioral tests employed. Examination of the brain after death revealed an unusual fissurational pattern on the orbital surface.